This invention relates to a cell film breaking apparatus for breaking cell films of foamed products made of urethane foam or the like to change independent foamed cells to continuous foamed cells. More particularly it relates to an apparatus for breaking cell films of foamed products made of metals, synthetic resins or the like having embedded reinforcing members in two or three dimensional shapes without any damage, deformation or the like of the reinforcing members, thereby greatly improving elasticity of the foamed products.
In order to break cell films of foamed products, various methods have been known. For example, foamed products are caused to pass through two rolls which are rotated in opposite directions to break cell films of the products. In another technique foamed products are accommodated in a vacuum chamber and pressure in the vacuum chamber is lowered to a negative pressure of the order of 400-700 mmHg to break cell films by the pressure difference across the cell films. In a further method, compressed air is forced into foamed products by means of a device such as an air pistol to break cell films.
In the method of using two rolls rotating in opposite directions for causing foamed products to pass therethrough, however, there is a risk of reinforcing members (if embedded in the products) being damaged or deformed. In this case, moreover, there is a difficulty that foamed products may be ruptured by embedded reinforcing members having three dimensional shapes. With the second method using the vacuum chamber under a negative pressure of the order of 400-700 mmHg, further, a ratio of broken cell films to unbroken cell films is a low value so that elasticity of the foamed products is not sufficiently improved. the third method using a device such as an air pistol, can only locally break cell films of foamed products, so that with bulky foamed products increased man-hours are imperative. Moreover, it is very difficult to break all the cell films uniformly or without omission. Worse still, the formed products are likely to be ruptured at locations where air is forced into the products.